Dataset Information

DNA Methylation-Based Epigenetic Repression of SLC22A4 Promotes Resistance to Cytarabine in Acute Myeloid Leukemia.

ABSTRACT: Reduced expression of the uptake transporter, OCTN1 (SLC22A4), has been reported as a strong predictor of poor event-free and overall survival in multiple cohorts of patients with acute myeloid leukemia (AML) receiving the cytidine nucleoside analog, cytarabine (Ara-C). To further understand the mechanistic basis of interindividual variability in the functional expression of OCTN1 in AML, we hypothesized a mechanistic connection to DNA methylation-based epigenetic repression of SLC22A4. We found increased basal SLC22A4 methylation was associated with decreased Ara-C uptake in AML cell lines. Pre-treatment with hypomethylating agents, 5-azacytidine, or decitabine, restored SLC22A4 mRNA expression, increased cellular uptake of Ara-C, and was associated with increased cellular sensitivity to Ara-C compared with vehicle-treated cells. Additionally, lower SLC22A4 methylation status was associated with distinct clinical advantages in both adult and pediatric patients with AML. These findings suggest a regulatory mechanism is involved in the interindividual variability in response to Ara-C, and provides a basis for the integration of hypomethylating agents into Ara-C-based treatment regimens.

SUBMITTER: Buelow DR

PROVIDER: S-EPMC7877866 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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DNA Methylation-Based Epigenetic Repression of SLC22A4 Promotes Resistance to Cytarabine in Acute Myeloid Leukemia.

Buelow Daelynn R DR Anderson Jason T JT Pounds Stanley B SB Shi Lei L Lamba Jatinder K JK Hu Shuiying S Gibson Alice A AA Goodwin Emily A EA Sparreboom Alex A Baker Sharyn D SD

Clinical and translational science 20200909 1

Reduced expression of the uptake transporter, OCTN1 (SLC22A4), has been reported as a strong predictor of poor event-free and overall survival in multiple cohorts of patients with acute myeloid leukemia (AML) receiving the cytidine nucleoside analog, cytarabine (Ara-C). To further understand the mechanistic basis of interindividual variability in the functional expression of OCTN1 in AML, we hypothesized a mechanistic connection to DNA methylation-based epigenetic repression of SLC22A4. We found ...[more]

PMID: 32905646

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Project description:BackgroundChildren with Down syndrome (DS) have increased risk for developing AML (DS-AMKL), and they usually experience severe therapy-related toxicities compared to non DS-AMKL. Refractory/relapsed disease has very poor outcome, and patients would benefit from novel, less toxic, therapeutic strategies that overcome resistance. Relapse/resistance are linked to cancer stem cells with high aldehyde dehydrogenase (ALDH) activity. The purpose of the present work was to study less toxic alternative therapeutic agents for relapsed/refractory DS-AMKL.MethodsFourteen AML cell lines including the DS-AMKL CMY and CMK from relapsed/refractory AML were used. Cytarabine (Ara-C), bortezomib (BTZ), disulfiram/copper (DSF/Cu2+) were evaluated for cytotoxicity, depletion of ALDH-positive cells, and resistance. BTZ-resistant CMY and CMK variants were generated by continuous BTZ treatment. Cell viability was assessed using CellTiter-Glo®, ALDH activity by ALDELUORTM, and proteasome inhibition by western blot of ubiquitinated proteins and the Proteasome-Glo™ Chymotrypsin-Like (CT-like) assay, apoptosis by Annexin V Fluos/Propidium iodide staining, and mutations were detected using PCR, cloning and sequencing.ResultsAra-C-resistant AML cell lines were sensitive to BTZ and DSF/Cu2+. The Ara-C-resistant DS-AMKL CMY cells had a high percentage of ALDHbright "stem-like" populations that may underlie Ara-C resistance. One percent of these cells were still resistant to BTZ but sensitive to DSF/Cu2+. To understand the mechanism of BTZ resistance, BTZ resistant (CMY-BR) and (CMK-BR) were generated. A novel mutation PSMB5 Q62P underlied BTZ resistance, and was associated with an overexpression of the β5 proteasome subunit. BTZ-resistance conferred increased resistance to Ara-C due to G1 arrest in the CMY-BR cells, which protected the cells from S-phase damage by Ara-C. CMY-BR and CMK-BR cells were cross-resistant to CFZ and MG-132 but sensitive to DSF/Cu2+. In this setting, DSF/Cu2+ induced apoptosis and proteasome inhibition independent of CT-like activity inhibition.ConclusionsWe provide evidence that DSF/Cu2+ overcomes Ara-C and BTZ resistance in cell lines from DS-AMKL patients. A novel mutation underlying BTZ resistance was detected that may identify BTZ-resistant patients, who may not benefit from treatment with CFZ or Ara-C, but may be responsive to DSF/Cu2+. Our findings support the clinical development of DSF/Cu2+ as a less toxic efficacious treatment approach in patients with relapsed/refractory DS-AMKL.

Project description:The gene encoding the tumor suppressor p53 is the most frequently mutated gene in cancers. However, p53 mutation is rare in acute myeloid leukemia (AML), and p53 is inactivated predominantly by aberrant expression of p53 regulators (such as MDM2). A previous study by the authors revealed that the ZCCHC10 protein suppressed MDM2‑mediated degradation of the p53 protein in lung cancer. However, the expression and role of the ZCCHC10 gene in AML have not been investigated. In the present study, it was found that ZCCHC10 expression was downregulated in bone marrow samples of AML patients and that ZCCHC10 expression was significantly and negatively correlated with the expression of the lncRNA SNHG1. Suppression of SNHG1 decreased ZCCHC10 promoter methylation and increased ZCCHC10 expression. Notably, there is a putative binding motif in SNHG1 with full complementarity to five sites surrounding the CpG island in the ZCCHC10 promoter. Overexpression of wild‑type SNHG1 promoted ZCCHC10 methylation, but overexpression of SNHG1 with deletion of the binding motif did not. Further study identified that SNHG1 simultaneously bound to the ZCCHC10 promoter and the DNA methyltransferases DNMT1 and DNMT3B. These results indicated that SNHG1 recruits DNMT1 and DNMT3B to the ZCCHC10 promoter, resulting in hypermethylation of the ZCCHC10 promoter. Kaplan‑Meier survival analysis showed that ZCCHC10 expression was positively associated with overall survival in AML patients. In vitro experiments demonstrated that ZCCHC10 increased p53 expression and suppressed AML cell proliferation and survival. In the xenograft mouse model, ZCCHC10 decreased the proliferation of leukemic cells, improved the survival of leukemic mice, and increased sensitivity to the BCL inhibitor venetoclax. In conclusion, ZCCHC10 expression is suppressed by SNHG1‑induced DNA methylation in AML. Downregulation of ZCCHC10 decreases p53 activation, promotes cell proliferation and survival, and thereby accelerates AML progression and the acquisition of venetoclax resistance. The present study identified a SNHG1/ZCCHC10/p53 signaling axis in AML that may be a therapeutic target in this malignancy.

Dataset Information

DNA Methylation-Based Epigenetic Repression of SLC22A4 Promotes Resistance to Cytarabine in Acute Myeloid Leukemia.

Publications

DNA Methylation-Based Epigenetic Repression of SLC22A4 Promotes Resistance to Cytarabine in Acute Myeloid Leukemia.

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